Summary of Significant Accounting Policies - Comprehensive Income (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss consists of foreign currency translation adjustments, net of tax	$ 43,665,000	$ 36,912,000
Net unrealized losses on available-for-sale investments, net of tax	3,006,000	4,382,000
Losses on currency swaps, net of gains on long-term intercompany loans	1,271,000	1,271,000
Net realized gains reclassified into current operations	236,000	4,119,000	$ 1,452,000
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized gains reclassified into current operations	$ 236,000	$ 4,119,000	$ 1,452,000